基于三臂自由摆动式活塞发动机的微型能源动力系统理论与实验研究

发布时间：2018-06-19 18:15

本文选题：微型能源动力系统 + 自由摆动式活塞发动机　；参考：《中国科学院工程热物理研究所》2017年博士论文

【摘要】：目前微型电脑、微型机器人及便携式检测仪器等微机电系统(Micro-Electro-Mechanical Systems,简称MEMS)的能源供给主要依靠电池。而传统电池存在功率密度低、质量与体积较大、供电时间短、存在有毒物质等问题,限制了 MEMS的进一步发展。故亟需研发能够替代传统电池的微型便携式能量供给单元。碳氢燃料具备诸多优点,例如能量密度高,燃料补充迅速,燃烧产物为水和二氧化碳对环境无危害。因而基于碳氢燃料燃烧的微型能源动力系统成为现今最具潜力的微型便携式能量供给单元替代方案。本文即是采用基于正丁烷燃烧的微热机方案来开发微发电系统取代传统电池能源。在众多微热机方案中,本文选取微型自由摆动式活塞发动机方案。该方案运转频率较低,活塞与气缸间磨损较小,对材料强度、轴承及润滑等无特殊要求。其扇形对置气缸结构可有效提高空间利用率,故系统功率密度较高。此外发动机为平面夹层结构,易于微加工和组装。因此该方案是有可能最先实用化的一种微型能源动力系统。本文基于三臂自由摆动式活塞发动机方案,开展了相关发动机系统理论与实验研究。本文第2章根据角动量、质量与能量等守恒方程推导出三臂摆式发动机/发电机系统零维数值计算模型的控制方程组,并且还分别给出了泄漏、散热与摩擦等损失模型以及燃烧模型。依托控制方程组、损失及燃烧模型给出了系统计算流程和收敛判据。然后,计算研究了摆式发动机的运转特性和热力循环过程。结果表明摆式发动机具备自启动能力无需外部辅助设备,且发动机启动迅速、运转过程无死点。两冲程摆式发动机稳态运转下,其热力循环可以近似为奥托循环。第3章完成了发动机负载、进气、燃烧特征及尺寸等参数对系统性能影响的理论研究。对于负载参数,固定质量负载时存在最佳电负载扭矩系数使得系统热效率或者指示功率最大。质量负载越大,发动机的电负载带载能力明显增强,且所能达到的热效率或者指示功率峰值也随之增大。进气参数影响方面,进气口直径较小时,随着进气压力提高,发动机热效率逐渐升高。而进气口直径较大时,热效率随着进气压力升高而下降。另一方面,进气压力与进气口直径越大,对应的指示功率越高。针对燃烧特征参数,燃烧持续时间一定时存在最优点火提前系数使得发动机热效率或者指示功率最大化。且热效率或者指示功率峰值随燃烧持续时间增大而显著下降。对于发动机尺寸影响,不考虑各种损失时指示功率与发动机尺寸呈现2次方正比关系。功率密度及运转频率则与尺寸呈现1次方反比关系。热效率和中心摆的摆幅几乎不随尺寸变化。此外第3章还对系统参数进行了敏感性分析。计算结果表明热效率对各参数的敏感性大小顺序是:燃烧持续时间、进气口直径进气压力电负载扭矩系数点火提前系数质量负载系数。而指示功率对各参数的敏感性大小顺序是:进气压力进气口直径燃烧持续时间质量负载系数电负载扭矩系数点火提前系数。第3章中还分别研究了泄漏、散热和摩擦等损失对系统性能的影响,并分别揭示了各损失的作用机理,为损失调控措施指明方向。并且还比较了各损失的影响大小。结果表明各损失对摆式发动机性能影响大小从高至低依次是:散热泄漏摩擦。其中摩擦影响远小于前两者。随着发动机尺寸缩小,泄漏对性能影响的增长速度最快,其次是散热损失。而摩擦损失增速缓慢且影响很小。在第4章中,基于简化的摆式发动机实验平台开展了相关原理性实验研究。首先利用电机带拖与无急回曲柄摇杆机构,开展了发动机气密性实验研究。并结合泄漏数值计算,揭示了影响泄漏的关键参数。发现可以通过减小间隙大小或者提高发动机运转频率来抑制泄漏损失。随后利用压缩空气模拟燃烧增压来驱动摆式发动机运转,完成了运转特性和能量转换方面的实验研究。实验验证了自由摆动式活塞发动机快速启停与快速负载响应等运转特性。获得了进气压力及阻力扭矩、充气时间、充气提前等参数对发动机压缩比、运转频率、(?)效率及指示功率等影响。结果表明进气压力越小、充气时间越短、充气适当提前时均利于发动机效率的提升。而对于阻力扭矩,其存在最佳值使得效率最大化。此外还完成了摆式发动机系统的发电实验,结果显示LED灯板负载两端输出电压峰值为5.8V,相应电功率峰值为6.3W。随后搭建起样机热态实验平台,包括闭环点火控制和多参数动态采集子系统等。采用正丁烷作为燃料,开展了样机的热态单次点火燃烧实验,验证了自由活塞、对置气缸交替运转的结构设计以及进气压缩与膨胀排气的两冲程奥托循环热力过程,表明自由摆动式活塞发动机方案具备技术可行性。此外基于开环控制等时间间隔点火控制系统,初步进行了样机的连续热态运转实验研究,发现点火延迟及进扫气效率是影响发动机运转特性的主要参数。最后基于简化样机的原理性实验研究成果,改进并优化了三臂摆式发动机的设计方案,完成了三臂式样机加工。
[Abstract]:At present, the energy supply of microcomputers, micro robots and portable detection instruments, such as Micro-Electro-Mechanical Systems (MEMS), is mainly dependent on the battery. The traditional batteries have the problems of low power density, large mass, large volume, short supply time, and toxic substances, which restrict the further development of MEMS. Therefore, the further development of the batteries is limited. It is necessary to develop a miniature portable energy supply unit that can replace traditional batteries. Hydrocarbon fuels have many advantages, such as high energy density, rapid fuel supply, and no harm to the environment by the combustion products of water and carbon dioxide. Therefore, the micro energy power system based on the combustion of hydrocarbon fuels becomes the most potential micro portable energy. In this paper, a microgenerator system based on n-butane combustion is used to develop a micro generation system to replace the traditional battery energy. In a number of microthermal machines, this paper selects the mini free swing piston engine scheme. The scheme is low operating frequency, less wear between piston and cylinder, material strength, bearing and There is no special requirement for lubrication. The sector opposed cylinder structure can effectively improve the space utilization, so the power density of the system is high. In addition, the engine is a planar interlayer structure, and it is easy to micromachining and assembling. Therefore, the scheme is a possible first practical micro energy power system. This paper is based on the three arm free swing piston engine. In the second chapter, the control equations of the zero dimension numerical model of the three arm pendulum engine / generator system are derived from the conservation equations of angular momentum, mass and energy, and the loss models, such as leakage, heat dissipation and friction, and the combustion model are also given. The equations, the loss and the combustion model give the system calculation flow and the convergence criterion. Then, the operation characteristics and thermodynamic cycle process of the pendulum engine are calculated and studied. The results show that the pendulum engine has self starting capacity without external auxiliary equipment, and the engine starts quickly, the operation process has no dead point. The steady state of the two stroke pendulum engine. Under the operation, the thermodynamic cycle can be approximated to the Otto cycle. The third chapter has completed the theoretical study of the influence of the engine load, intake, combustion characteristics and size on the system performance. For the load parameters, the optimal load torque coefficient in the fixed mass load makes the system thermal efficiency or indicating power maximum. The greater the mass load, the greater the mass load, The electric load carrying capacity of the engine is obviously enhanced, and the thermal efficiency or the peak value of the indicated power is also increased. As the intake pressure increases, the engine thermal efficiency increases with the intake pressure increasing. While the intake pressure is larger, the thermal efficiency decreases with the increase of the intake pressure. The other side is reduced. The higher the inlet pressure and the inlet diameter, the higher the corresponding indicator power. For the combustion characteristic parameters, the optimal ignition advance coefficient makes the engine thermal efficiency or the indication power maximized when the combustion duration is certain. And the thermal efficiency or the peak value of the indicated power decreases significantly with the increase of combustion duration. For the engine, the engine is significantly reduced with the combustion duration. The relationship between the indicator power and the size of the engine has 2 square positive ratio. The power density and the operating frequency are in inverse proportion to the size of the 1 times. The thermal efficiency and the pendulum of the central pendulum almost do not change with the size. In addition, the sensitivity analysis of the system parameters is also carried out in the third chapter. The calculation results show that the thermal efficiency is correct. The order of the sensitivity of each parameter is the burning duration, the inlet pressure of the inlet pressure, the torque coefficient of the electric load and the mass load coefficient of the ignition advance coefficient, and the order of the sensitivity of the indicator power to the parameters is: the constant time mass load coefficient of the inlet pressure intake, the ignition advance coefficient of the torque coefficient of the electric load. In the third chapter, the effects of leakage, heat dissipation and friction on the performance of the system are also studied, and the mechanism of each loss is revealed, and the direction of the loss control measures is pointed out. And the impact of each loss is also compared. The results show that the effect of loss on the performance of the pendulum engine from high to low is: heat dissipation and leakage. Friction effect is far less than the former two. With the reduction of engine size, the effect of leakage on the performance is the fastest, followed by heat loss. And the friction loss is slow and small. In the fourth chapter, the experimental research on the simplified pendulum engine experimental platform is carried out. An experimental study of the engine airtightness is carried out without an emergency crank rocker mechanism, and the key parameters affecting the leakage are revealed with the numerical calculation of leakage. It is found that the leakage loss can be suppressed by reducing the gap size or increasing the engine operating frequency. Then the compressed air model is used to drive the tilting engine to drive the engine. The experimental research on the operation characteristics and energy conversion has been completed. The experiments verify the operation characteristics of the fast start stop and fast load response of the free swing piston engine. The effects of the intake pressure and resistance torque, the inflating time and the inflating advance on the engine compression ratio, the transfer frequency, the (?) efficiency and the indicated power are obtained. It is shown that the smaller the intake pressure, the shorter the inflating time and the appropriate advance for the aeration are all beneficial to the efficiency of the engine. And for the resistance torque, the best value has the maximum efficiency. In addition, the power generation experiment of the pendulum engine system has been completed. The results show that the peak of the output voltage of the two end of the LED lamp plate is 5.8V, and the peak value of the corresponding electric power is at the peak value. 6.3W. then set up a prototype thermal experimental platform, including closed loop ignition control and multi parameter dynamic acquisition subsystem. Using n-butane as fuel, a single ignition combustion experiment of the prototype was carried out. The structure design of the free piston, the alternate operation of the opposed cylinder and the two stroke Otto cycle of the air intake compression and the expansion exhaust were verified. The cyclic thermodynamic process shows that the scheme of the free swing piston engine has technical feasibility. In addition, based on the time interval ignition control system such as open loop control, the experimental research on the continuous hot state operation of the prototype is carried out preliminarily. It is found that the ignition delay and the inlet gas efficiency are the main parameters affecting the engine running characteristics. Finally, the simplified prototype is based on the simplified prototype. Based on the experimental research results, the design scheme of the three arm pendulum engine was improved and optimized, and the three arm prototype was completed.
【学位授予单位】：中国科学院工程热物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TK403

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